SUMMARY ......................................................... 1
1 INTRODUCTION ............................................... 9
1.1 Inorganic sulfur compounds in the environment .............. 9
1.2 Sulfur transformations in constructed wetlands ............ 10
1.2.1 Dissimilatory sulfate reduction .................... 12
1.2.2 Assimilatory sulfate reduction ..................... 13
1.2.3 Mineral precipitation of sulfate ................... 14
1.2.4 Precipitation of metal sulfides .................... 14
1.2.5 Emission of hydrogen sulfide ....................... 15
1.2.6 Oxidation of sulfide ............................... 15
1.2.7 Sulfur disproportionation .......................... 16
1.2.8 Sulfur transformations in the interconnections
with wetland plants and other important
redox processes .................................... 18
1.2.9 Sulfur transformations in constructed
wetlands for sulfate-rich wastewater treatment
applications ....................................... 21
1.3 Sulfur oxidizing bacteria ................................. 22
1.3.1 Colorless sulfur oxidizing bacteria ................ 22
1.3.2 Colored sulfur oxidizing bacteria .................. 26
1.3.3 Microbial sulfur oxidation pathways with gene
systems involved ................................... 29
1.3.4 Sulfur oxidizing bacteria in wastewater
treatment .......................................... 32
1.4 Research gaps and objective of this study ................. 34
2 MATERIALS AND METHODS ..................................... 36
2.1 Description of laboratory-scale constructed wetland
models .................................................... 36
2.2 Experimental set-up ....................................... 37
2.3 Conceptual framework ...................................... 39
2.4 Chemical analysis and calculations ........................ 45
2.4.1 Sulfur compounds ................................... 45
2.4.2 TOC, acetate and benzoate .......................... 45
2.4.3 Nitrogen species ................................... 46
2.4.4 Redox potential, temperature and pH ................ 46
2.4.5. Dissolved oxygen ................................... 46
2.4.6 Calculations ........................................ 46
2.5 Molecular analysis ........................................ 48
2.5.1 DNA isolation and quantification ................... 48
2.5.2 PCR amplification of the 16S rRNA gene ............. 49
2.5.3 Agarose gel electrophoresis ........................ 50
2.5.4 454 Pyrosequencing ................................. 50
2.5.5 Quantitative PCR ................................... 57
3 RESULTS AND DISCUSSION .................................... 58
3.1 Dynamics of sulfur compounds in wetland models ............ 58
3.2 Sulfur transformations in the interconnections with
other important redox processes ........................... 67
3.2.1 Nitrogen transformations ........................... 67
3.2.2 Behavior of organic carbon sources: acetate,
benzoate, TOC ...................................... 71
3.3 Other physicochemical parameters correlating with sulfur
transformations ........................................... 74
3.3.1 pH ................................................. 74
3.3.2 Redox potential .................................... 76
3.3.3 Dissolved oxygen ................................... 78
3.3.4 Effects of sulfide on growth of wetland plants ..... 79
3.4 Microbial community analysis in wetland models ............ 83
3.4.1 SOB and SRB abundance and the correlations with
behavior of sulfur compounds ....................... 83
3.4.2 Quantitative qPCR targeting 16S rRNA genes ......... 95
3.4.3 Microbial community compositions .................. 100
4 CONCLUDING REMARKS ....................................... 106
References .................................................... 109
Appendix ...................................................... 123
Acknowledgement ............................................... 168
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